The Siemens 5SU1354-0LV40 is an FI/LS combination unit — an RCBO that packs residual-current protection (Type AC, 30 mA) and overcurrent protection (B-curve, 40 A) into a single 1+N-pole module. That 70 mm depth (D=70MM) keeps the assembly compact on the DIN rail, which matters when you're squeezing multiple circuits into a tight residential or light-commercial load center.
What the ratings mean for fit
The 30 mA IΔn is the standard sensitivity for socket-outlet circuits in most domestic and commercial installations — it catches the leakage a person might draw through a hand-to-ground fault before the heart goes into fibrillation. The 10 kA breaking capacity (10 KA) tells you it can safely interrupt a short-circuit fault up to that level; in a typical TN system with a 40 A B-curve MCB section, that's enough headroom for most final subcircuits without needing an upstream current-limiting device. The B characteristic (B 40) means the magnetic trip fires at 3 to 5 times rated current (120–200 A), which suits resistive and general-purpose loads — lighting, heaters, socket outlets — where inrush isn't heavy. The G-type designation points to a specific Siemens variant within the 5SU1 family, likely differing in the neutral-switching arrangement or terminal design from the standard F-type.